During the printing process, signatures, e.g., folded printed sheets for forming sections of a book, pamphlet, newspaper, etc., initially transported at high speed in a folder machine for folding a continuous web of printed paper, must be slowed down for subsequent processing in order to prevent blockages from occurring during folding, especially when a quarter fold is to be made.
For example, brush systems and vacuum devices which exercise a speed reducing force on a signature are well known and serve to reduce signature speed.
Slow-down cylinders have also been used to reduce the speed of a signature. Typically, two cylinders are placed in series, leading the signature to the quarter fold, and each of them produces a speed reduction of 30%. This method, however, is complex and thus expensive.
Sets of belts which operate from high speed to low speed are also known. Signatures are transported from high-speed belts to low-speed belts which receive them. This method, however, causes a sudden change in the speed of a signature, with no gradual transition, and thus the signature is often transferred without precision in a partly uncontrolled manner which leads to inaccuracy and blockages.
One advantage of the present invention is that the signatures are gradually slowed down by an assembly of partial pulleys prior to folding. This minimizes blockages and other inaccuracies which occur when the signatures are suddenly slowed down.
Another advantage of the present invention is that the signatures are continuously supported and conveyed throughout their travel. Thus, blockages and other inaccuracies are further minimized.